Silyl selenides

The analogous capping of cadmium selenide particles by organo(silyl)-selenides in reversed micelles will be discussed in Sect. 4.4. 

CdSe or CdS growth were arrested by capping with (organo)(silyl)selenide or thiophenolate ions the process was a living polymerization... 

Oxidation of an a-silyl selenide with hydrogen peroxide leads to an aldehyde, silanol and selenol as the primary products [253]. Evidently, the fragmentation proceeds only after contrapolarization at Se, the intermediate now having an a-d-a array. 

The selenium-metal exchange proved a valuable 77), reaction for the synthesis of a-lithio cyclopropylsilane from a-methylseleno-a-silylcyclopropane and n-BuLi (Scheme 20). This organometallic is in fact the first a-lithiated silane bearing two alkylsubstituents to be prepared 77,105). The starting a-silyl selenide is readily avail-... 

In the case of 2-decyl-l-lithio-l-(methylseleno)cyclopropane and methyl iodide, the alkylation leads to a 1 1 mixture of the stereoisomers35 (Scheme 16), but it is not known which of the alkylation or the lithiation steps is not stereoselective as both stereoisomers of this cyclopropyllithium are formed. Trimethylsilyl chloride reacts efficiently with a-lithiocyclobutyl selenides35 and a-lithiocyclopropyl selenides 77 and produces the corresponding a-silyl selenides (Scheme 23). Trimethyl-silyl-(methylseleno)cyclopropame was found77 to be a powerful precursor of a-silylcyclopropyl lithium which cannot be directly alkylated 78,94), as already mentioned. 

In a very similar manner, (l-silylcyclopropyl)lithiums can be used to alkylate a-selanyl aldehydes and the products subjected to dehydroxyselenation to give alkenyl(silyl)cyclopropanes. Here, too, the f-isomer is obtained in contrast to the Z orientation in the Wittig olefination of the corresponding 1-silylcyclopropanecarbaldehydes. Thus, l-[( )-oct-l-enyl]-l-(trimethylsilyl)cy-clopropane (8) was obtained in 79% yield from the corresponding hydroxy silyl selenide 7. 

The reaction of 52 with BuLi followed by alkylation with alkyl halides gave the silyl selenides 53. The repetition of a similar operation with BuLi and acyl chlorides afforded selenol esters in good yields. Selenol ester was also obtained in a good yield when the order of the alkylation/acylation sequence was changed. 

Indeed, the first example of other Lewis add, except for TiCU and BX3, catalyzed chalcogenide-MBH reactions dates back to the 1980s, when Noyori et al. first demonstrated that the conjugated addition of a silyl selenide to an enone catalyzed by TMSOTf provided a silyl enol ether, which can be successfully engaged in subsequent Mukaiyama retro-aldol reactions with various... 

A soln. of bis[isopropyl(thiocarbonyl)] sulfide in hexane added to a soln. of freshly prepared Na-benzeneselenolate in 3 1 dichloromethane/methanol at 0°, and stirred for 30 min - Se-phenyl 2-propanecarboselenothioate. Y 77%. F.e., also from thiocar-boxylic acid chlorides (with selenolates or silyl selenides), and reactions s. S. Kato et al.. Bull. Chem. Soc. Japan 61, 3931-J2 (1988). 

Selenides s. Silyl-selenides, Stannyl-Seleninic acids... 

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